Humpb ack whales ( Megaptera novaeangliae) migrate annually from feeding grounds in the Antarctic to breeding grounds in warm tropical waters, such as off North Western Australia. The humpback whales that migrate up the West Australian coast are called the Group IV humpback whales (sometimes referred to as breeding stock D). The distance of the annual migration of the Group IV whales is 6,000 nautical miles (11,000km). The humpbacks do not feed on this migration. The population of the Group IV humpback whales is about 30,000 which is the largest humpback whale population in the southern hemisphere. The Group IV humpback whales calve along the Kimberley Coast and Exmouth Gulf is a resting ground for them. At its peak, Exmouth Gulf hosts a whale density of one whale per square kilometre (2008 data). This is the highest whale density along the West Australian coast, including the calving grounds along the Kimberley coast, and the highest density of humpback whales found in the southern hemisphere.
The humpback whale was hunted almost to extinction in the past. A whaling station in Carnarvon, south of the Ningaloo Coast World Heritage Area, contributed to the humpbacks’ demise in the region. The humpback became a protected species in Australia in 1963, at which time there was only 5 - 6% of the pre-whaling population remaining.
Humpback whales grow to be about 52 feet long or about as long as a touring boat. The four chambered heart of the average humpback whale weighs about 430 pounds - about as much as three average adult human beings.
Just like every other animal, whales’ behaviour reflects their feelings and thoughts.
How they act on the surface directly relates to whether they are feeling social, relaxed or threatened.
Did you know?
- The humpback is the fifth largest of the great whales.
- It is named for its small, hump-like dorsal fin that shows as the whale arches its back while diving.
- The humpback is easily distinguished from other whales by its long, knobbly flippers (up to 5m) which may be a 1/3 of its body length.
- Their bodies are black on top and white underneath, with long pleats running down their throats which let their throats expand as they feed.
- A humpback has no teeth and feeds by taking an enormous gulp of water and straining zooplankton out of the water through its baleen, the bristly, comb-like horny plates hanging from its palate.
- An adult humpback has 2 lungs (each the size of a small car) which are emptied and refilled in less than 2 seconds.
- A layer of blubber up to 50cm thick keeps them warm in cold seas.
- During the breeding season, humpback males sing the longest and most complex songs in the animal kingdom.
- The female is probably larger than the male because of the long fast required while bearing and feeding her calf during the annual migration.
- Humpback mother’s milk has a 35% fat content and is pink in colour. A nursing calf drinks around 240L of milk per day and can gain more than 45kg a day during its first weeks of life.
- As they breathe voluntarily (meaning humpbacks have to remember to breathe, unlike human beings) and have to surface to breathe through 2 blowholes on top of their heads, they sleep by only shutting off 1/2 of their brain at a time.
- Humpbacks travel in groups known as pods.
Humpback whales pass by Gnaraloo from July to October, often engaging in spectacular displays breaching the water and slapping their pectoral fins.
A 10m humpback skeleton was collected in front of the Gnaraloo Homestead area during July 2012. Work is underway to articulate the skeleton for display at Gnaraloo.